Antimicrobial resistance of Enterococcus spp. isolates from raw beef and meat products.

E. faecalis (67%) and E. faecium (13.7%) were most frequently isolated among enterococci that contaminate cooled and frozen processed meat, follow-up heat-treated meat products and unheated fermented dry salami. Most isolates of both species were resistant to cephalothin (95 and 83 %) and clindamycin (77 and 67%, respectively). Furthermore, E. faecalis and E. faecium isolates were resistant to erythromycin (44 and 72%), tetracycline (34.5 and 17.4%), and streptomycin (13.3 and 4.3%, respectively). Only a few of the isolates were resistant to ampicillin, ampicillin-sulbactam, chloramphenicol, and vancomycin while all isolates were susceptible to gentamicin, penicillin, and teicoplanin. During the production of heat-treated meat products, numbers of resistant isolates increased in spite of the decreasing enterococcal contamination of the samples. An opposite situation was found in the production of fermented dry salami.

Beef carcass contamination in a slaughterhouse and prevalence of resistance to antimicrobial drugs in isolates of selected microbial species.

Meat contaminating bacteria may be the direct cause of foodborne diseases and represent a potential cause for the drug resistance of human pathogenic agents. The prevalence and resistance to 17 antimicrobial drugs of isolates of selected bacterial species were investigated in 70 swabs of beef carcasses and 70 subsequent samples of beef meat. Molecular techniques (coagulase gene typing Staphylococcus aureus and original gene typing Escherichia coli) were used in the differentiation of isolates. Carcasses were already contaminated after evisceration, least frequently with S. aureus strains (7.5% of samples), most frequently with coagulase-negative staphylococci strains (52.2% of samples). During carcass processing, contamination with resistant or polyresistant strains of S. aureus and E. coli significantly increased (P<0.01). Gene typing isolates of S. aureus and E. coli indicated that the strains probably originated in the processing plant.